.stu-selector-container {
    display: flex;
}

.stu-selector-container div {
    display: inline-block;
}

.stu-selector-groups {
    width: 100px;
}

.stu-selector-students {
    flex: 1;
    width: 100px;
}

.stu-selector-groups div,
.stu-selector-students div {
    display: block;
}

.stu-selector-groups-item-span,
.stu-selector-students-item-span {
    font-size: 15px;
    position: relative;
}

.stu-selector-groups-item-span::before,
.stu-selector-students-item-span::before {
    position: absolute;
    content: "";
    width: 0%;
    left: 0;
    transition: 0.3s;
    bottom: -4px;
    height: 3px;
}

.stu-selector-groups-item,
.stu-selector-students-item {
    line-height: 30px;
    cursor: pointer;
}

.stu-selector-groups-item:hover .stu-selector-groups-item-span::before {
    background: rgb(255, 0, 0);
    width: 100%;
}

.stu-selector-students-item:hover .stu-selector-students-item-span::before {
    background: rgb(39, 101, 194);
    width: 100%;
}